We are going to London today and have just worked out that if we buy a family railcard it will cost the same as if we just got a one day travelcard. So I wondered if I could buy a railcard online and then use it today? Our station is fairly remote, so it's unlikely the ticket office will be open, so you have to buy tickets via a machine. Will the machine have the option to include the railcard? I don't want to buy one online and then still have to pay the full price iyswim.